A Frequency-Agile Filtering Metasurface Antenna with Single, Dual, and Wideband Reconfigurability

This paper presents the design and implementation of a compact reconfigurable filtering metasurface antenna that integrates wideband operation, high gain, and frequency selectivity. The proposed structure incorporates multi-folded U-shaped slots, defected ground structures (DGS), and coplanar parasitic patches to achieve strong out-of-band suppression and enhanced radiation performance. Dynamic frequency reconfigurability is enabled by integrating PIN diodes, allowing the antenna to adapt to varying operational requirements in real-time. The antenna supports eight distinct frequency states controlled by PIN diode switching. The filtenna exhibits single-band narrowband responses at 7 GHz, $7.2 \mathrm{GHz}, 7.5 \mathrm{GHz}$, and 7.45 GHz, with bandwidths ranging from 0.03 GHz to 0.41 GHz. Additionally, the antenna demonstrates dual-band functionality at 6.4 GHz and 7.45 GHz, at 7.3 GHz and 7.5 GHz. It also exhibited a wideband response covering 0.7 GHz from 6.9 to 7.6 GHz. The size of the filtenna is $33 \times 33 \times 1.778$ $\mathrm{mm}^{3}$. Experimental results confirm that the proposed design successfully combines frequency agility, compactness, and high performance, making it a helpful design for modern wireless communication systems, radar applications, and cognitive radio.